Do you need to wear a sweater in your air-conditioned home? The central air conditioner may feel great on very hot days, but chilly and uncomfortable on mild days. An innovation in central air conditioning alleviates the problem. Two-stage cooling provides two levels of output for better temperature control and indoor air quality. The outdoor unit, or compressor, handles the two-stage cooling, running at a low setting most of the time, which should be enough to meet routine household demands.